SAN FRANCISCO (Reuters) - Amazon.com Inc said on Monday that its $199 Kindle Fire HD tablet has been the best-selling product on the company's website since the gadget went on sale more than a month ago.

Amazon started selling a range of new Kindle Fires on September 6 and the company said the 7-inch HD model has out-sold all other products on Amazon worldwide since then.

Amazon did not disclose actual sales numbers, but a spokeswoman for the company said the top-seller status was based on unit sales.

Amazon Chief Executive Jeff Bezos recently told the BBC that it sells the tablets at cost, hoping to generate profits when customers use the devices to buy products and services from the company.

The announcement came as Apple Inc prepares to launch a smaller, cheaper tablet of its own on Tuesday. The device, dubbed the iPad Mini, may challenge Amazon's success at the lower end of the booming tablet market.